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          <th colspan="3" align="center">DbEnv::txn_stat()</th>
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          <th width="60%" align="center">Chapter 13. 
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            <h2 class="title" style="clear: both"><a id="txnstat"></a>DbEnv::txn_stat()</h2>
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      <pre class="programlisting">#include &lt;db_cxx.h&gt;

int
DbEnv::txn_stat(DB_TXN_STAT **statp, u_int32_t flags); </pre>
      <p>
         The <code class="methodname">DbEnv::txn_stat()</code> method returns the transaction subsystem
         statistics.
    </p>
      <p>
         The <code class="methodname">DbEnv::txn_stat()</code> method creates a statistical structure of type
         <code class="literal">DB_TXN_STAT</code> and copies a pointer to it into a user-specified memory
         location.
    </p>
      <p>
         Statistical structures are stored in allocated memory.  If
         application-specific allocation routines have been declared (see
         <a class="xref" href="envset_alloc.html" title="DbEnv::set_alloc()">DbEnv::set_alloc()</a> 
         for more information), they are used to allocate the memory;
         otherwise, the standard C library <span class="bold"><strong>malloc</strong></span>(3) is used.  The caller is responsible
         for deallocating the memory.  To deallocate the memory, free the
         memory reference; references inside the returned memory need not be
         individually freed.
    </p>
      <p>
        The following DB_TXN_STAT fields will be filled in:
    </p>
      <div class="itemizedlist">
        <ul type="disc">
          <li>
            <p>
                    <span class="bold"><strong>u_int32_t st_inittxns;</strong></span>
                </p>
            <p>
                    The initial number of transactions configured.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>DB_LSN st_last_ckp;</strong></span>
                </p>
            <p>
                    The LSN of the last checkpoint.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>u_int32_t st_last_txnid;</strong></span>
                </p>
            <p>
                    The last transaction ID allocated.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>u_int32_t st_maxnactive;</strong></span>
                </p>
            <p>
                    The maximum number of active transactions at any one time.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>u_int32_t st_maxnsnapshot;</strong></span>
                </p>
            <p>
                    The maximum number of transactions on the snapshot list at any one
                    time.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>u_int32_t st_maxtxns;</strong></span>
                </p>
            <p>
                    The maximum number of active transactions configured.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>uintmax_t st_naborts;</strong></span>
                </p>
            <p>
                    The number of transactions that have aborted.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>u_int32_t st_nactive;</strong></span>
                </p>
            <p>
                    The number of transactions that are currently active.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>uintmax_t st_nbegins;</strong></span>
                </p>
            <p>
                    The number of transactions that have begun.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>uintmax_t st_ncommits;</strong></span>
                </p>
            <p>
                    The number of transactions that have committed.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>u_int32_t st_nrestores;</strong></span>
                </p>
            <p>
                    The number of transactions that have been restored.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>u_int32_t st_nsnapshot;</strong></span>
                </p>
            <p>
                    The number of transactions on the snapshot list.  These are
                    transactions which modified a database opened with 
                    <a class="link" href="dbopen.html#dbopen_DB_MULTIVERSION">DB_MULTIVERSION</a>,
                    and which have committed or aborted, but the copies of pages they
                    created are still in the cache.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>uintmax_t st_region_nowait;</strong></span>
                </p>
            <p>
                    The number of times that a thread of control was able to obtain the
                    transaction region mutex without waiting.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>uintmax_t st_region_wait;</strong></span>
                </p>
            <p>
                    The number of times that a thread of control was forced to wait before
                    obtaining the transaction region mutex.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>roff_t st_regsize;</strong></span>
                </p>
            <p>
                    The region size, in bytes.
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>time_t st_time_ckp;</strong></span>
                </p>
            <p>
                    The time the last completed checkpoint finished (as the number of
                    seconds since the Epoch, returned by the IEEE/ANSI Std 1003.1 (POSIX)
                    <span class="bold"><strong>time</strong></span> function).
                </p>
          </li>
          <li>
            <p>
                    <span class="bold"><strong>DB_TXN_ACTIVE *st_txnarray;</strong></span>
                </p>
            <p>
                    A pointer to an array of <span class="bold"><strong>st_nactive</strong></span>
                    DB_TXN_ACTIVE structures, describing the currently active
                    transactions. The following fields of the DB_TXN_ACTIVE structure will
                    be filled in:
                </p>
            <div class="itemizedlist">
              <ul type="circle">
                <li>
                  <p>
                                <span class="bold"><strong>u_int32_t txnid;</strong></span>
                            </p>
                  <p>
                                The transaction ID of the transaction.
                            </p>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>u_int32_t parentid;</strong></span>
                            </p>
                  <p>
                                The transaction ID of the parent transaction (or 0, if no parent).
                            </p>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>pid_t pid;</strong></span>
                            </p>
                  <p>
                                The process ID of the originator of the transaction.
                            </p>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>db_threadid_t tid;</strong></span>
                            </p>
                  <p>
                                The thread of control ID of the originator of the transaction.
                            </p>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>DB_LSN lsn;</strong></span>
                            </p>
                  <p>
                                The current log sequence number when the transaction was begun.
                            </p>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>DB_LSN read_lsn;</strong></span>
                            </p>
                  <p>
                                The log sequence number of reads for snapshot transactions.
                            </p>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>u_int32_t mvcc_ref;</strong></span>
                            </p>
                  <p>
                                The number of buffer copies created by this transaction that remain
                                in cache.
                            </p>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>u_int32_t priority;</strong></span>
                            </p>
                  <p>
                                This transaction's deadlock resolution priority.
                            </p>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>u_int32_t status;</strong></span>
                            </p>
                  <p>
                                Provides one of the following constants,
                                indicating the transaction status:
                            </p>
                  <table class="simplelist" border="0" summary="Simple list">
                    <tr>
                      <td>TXN_ABORTED</td>
                    </tr>
                    <tr>
                      <td>TXN_COMMITTED</td>
                    </tr>
                    <tr>
                      <td>TXN_NEED_ABORT</td>
                    </tr>
                    <tr>
                      <td>TXN_PREPARED</td>
                    </tr>
                    <tr>
                      <td>TXN_RUNNING</td>
                    </tr>
                  </table>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>u_int32_t xa_status;</strong></span>
                            </p>
                  <p>
                                Provides one of the following constants, which indicate the
                                XA status:
                            </p>
                  <table class="simplelist" border="0" summary="Simple list">
                    <tr>
                      <td>TXN_XA_ACTIVE</td>
                    </tr>
                    <tr>
                      <td>TXN_XA_DEADLOCKED</td>
                    </tr>
                    <tr>
                      <td>TXN_XA_IDLE</td>
                    </tr>
                    <tr>
                      <td>TXN_XA_PREPARED</td>
                    </tr>
                    <tr>
                      <td>TXN_XA_ROLLEDBACK</td>
                    </tr>
                  </table>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>u_int8_t gid[DB_GID_SIZE];</strong></span>
                            </p>
                  <p>
                              If the transaction was prepared using 
                              <a class="xref" href="txnprepare.html" title="DbTxn::prepare()">DbTxn::prepare()</a>, then
                              <span class="bold"><strong>gid</strong></span> contains the
                              transaction's Global ID. Otherwise,
                              <span class="bold"><strong>gid's</strong></span> contents are undefined.
                            </p>
                </li>
                <li>
                  <p>
                                <span class="bold"><strong>char name[];</strong></span>
                            </p>
                  <p>
                                If a name was specified for the transaction, up to the first 50 bytes
                                of that name, followed by a nul termination byte.
                            </p>
                </li>
              </ul>
            </div>
          </li>
        </ul>
      </div>
      <p>
           The <code class="methodname">DbEnv::txn_stat()</code> method may not be called before the 
           <a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a>  method is called.
    </p>
      <p>
         The <code class="methodname">DbEnv::txn_stat()</code> <span>
            
            <span>
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.
            </span>
        </span>
    </p>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp10389544"></a>Parameters</h3>
            </div>
          </div>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp10388704"></a>statp</h4>
              </div>
            </div>
          </div>
          <p>
                          The <span class="bold"><strong>statp</strong></span> parameter references memory
                          into which a pointer to the allocated statistics structure is copied.
                     </p>
        </div>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp10410832"></a>flags</h4>
              </div>
            </div>
          </div>
          <p>
                          The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
                          or the following value:
                     </p>
          <div class="itemizedlist">
            <ul type="disc">
              <li>
                <p>
                  <code class="literal">DB_STAT_CLEAR</code>
            </p>
                <p>
                Reset statistics after returning their values.
            </p>
              </li>
            </ul>
          </div>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp10407152"></a>Errors</h3>
            </div>
          </div>
        </div>
        <p>
                         The <code class="methodname">DbEnv::txn_stat()</code> <span>
            
            <span>
                method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a> 
                exception, encapsulating one of the following non-zero errors, or return one
                of the following non-zero errors:
            </span>
        </span>
                    </p>
        <div class="sect3" lang="en" xml:lang="en">
          <div class="titlepage">
            <div>
              <div>
                <h4 class="title"><a id="idp10420928"></a>EINVAL</h4>
              </div>
            </div>
          </div>
          <p>
                An invalid flag value or parameter was specified.
            </p>
        </div>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp10419632"></a>Class</h3>
            </div>
          </div>
        </div>
        <p>
                 <a class="link" href="env.html" title="Chapter 5.  The DbEnv Handle">DbEnv</a>, <a class="link" href="txn.html" title="Chapter 13.  The DbTxn Handle">DbTxn</a> 
            </p>
      </div>
      <div class="sect2" lang="en" xml:lang="en">
        <div class="titlepage">
          <div>
            <div>
              <h3 class="title"><a id="idp10303000"></a>See Also</h3>
            </div>
          </div>
        </div>
        <p>
                     <a class="xref" href="txn.html#txnlist" title="Transaction Subsystem and Related Methods">Transaction Subsystem and Related Methods</a> 
                </p>
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